Preceding material for pumping

ABSTRACT

The purpose of the present invention is to provide a preceding material for pumping, a feeding of a very small amount thereof being capable of extending the pumping distance. The preceding material for pumping includes an added cellulose nanofiber and having calcium carbonate as a main component. The present invention enables a thin lubricant layer of a uniform thickness to be formed inside a pipe even when the pipe has a slightly roughened inner surface due to, for example, residues of solidified cement paste or the like, allowing the pumping distance to be extended. Thus, the present invention is suitable, for example, for casting ready-mixed concrete at various construction sites.

TECHNICAL FIELD

The present invention relates to a preceding material for pumping, whichis used during pumping and casting of ready-mixed concrete by using, forexample, a ready-mixed concrete pumping vehicle. More particularly, thepresent invention relates to the preceding material for pumping, inwhich the pumping distance can be extended by using cellulose nanofiber(CNF).

BACKGROUND ART

Ready-mixed concrete pumping vehicles are used at various constructionsites, as a means for pumping and casting of ready-mixed concrete into apredetermined place. The ready-mixed concrete pumping vehicle isprovided with a hopper, a pump and a boom, and a piping is connected toan outlet of the pump. The piping is laid along the boom, and elongatingtoward a predetermined place into which the ready-mixed concrete ispumped. A ready-mixed concrete mixer vehicle feeds the ready-mixedconcrete into the hopper, and the ready-mixed concrete is pumped to andcasted in the predetermined place by the pump and piping.

When pumping of the ready-mixed concrete, if the ready-mixed concrete ispoured directly into the piping, the water content in the ready-mixedconcrete is taken away to the piping, and as a result, a coarseaggregate in the ready-mixed concrete tends to proceed first. Thissituation has a risk of clogging at a delivery end of pumping, due tointertangling of the coarse aggregate.

Accordingly, in conventional arts, before starting of pumping of theready-mixed concrete, a preceding material for pumping is filled intothe hopper, so that the preceding material for pumping may be pouredinto the piping in advance of the ready-mixed concrete. The precedingmaterial for pumping in such a case is a cement paste, which is amixture of water and cement.

However, when the cement paste is used as the preceding material forpumping, a large volume (for example, about 0.5 m³) of cement paste isrequired, and furthermore, there is also a problem of inevitable andcomplicated work of mixing of water and cement.

Moreover, when the cement paste is used as the preceding material forpumping, there is also a problem that the preceding material may bemixed with the ready-mixed concrete, which causes deterioration ofcompressive strength after curing of the ready-mixed concrete.

In addition, there is also a problem that the large volume of cementpaste, which has been used as the preceding material for pumping, willdirectly become the industrial waste.

For the purpose of solving of the above problem, some fresh types ofpreceding materials for pumping have been proposed, for example, asdisclosed in Patent Document 1 and Patent Document 2. Each of thesepreceding materials for pumping is a water-absorbing resin, such as acrosslinked composition of polyacrylic acid, a crosslinked compositionof polyacrylate, a crosslinked composition of acrylic acid-vinyl alcoholcopolymer, a crosslinked composition of acrylate-vinyl alcoholcopolymer, a crosslinked composition of starch-acrylic acid graftcopolymer, a crosslinked composition of starch-acrylate graft copolymer,a crosslinked composition of isobutylene-maleic acid copolymer, acrosslinked composition of isobutylene-maleate copolymer, a crosslinkedcomposition of styrene-maleic anhydride copolymer, a crosslinkedcomposition of saponified vinyl ester-ethylenic unsaturated carboxyliccopolymer, a crosslinked composition of saponified vinyl ester-ethylenicunsaturated carboxylic derivative copolymer, a crosslinked compositionof polyethylene oxide, a crosslinked composition of ethyleneoxide-propylene oxide copolymer, water-absorbing urethane, etc.

REFERENCE DOCUMENTS OF CONVENTIONAL ART Patent Document(S)

-   Patent Document 1: Official Gazette, J P 2000-34461 A.-   Patent Document 2: Official Gazette, J P 2016-74196 A.

SUMMARY OF THE INVENTION Problems to be Solved by Invention

However, the above structures of the conventional arts have thefollowing problems:

Namely, likewise the case of the inventions as disclosed in PatentDocument 1 and Patent Document 2, where the water-absorbing resin isused instead of the cement paste, then, the problems with the use of thecement paste, i.e. the problem of requiring a large volume of cementpaste and the problem of inevitable and complicated work, may be solved.However, the effect of such a solution is limited, and in the case ofpumping for the longer distance, or in the case of pumping through thepiping of which inner surface is somewhat rough, there is still a riskof clogging of the piping.

In the light of the above problems, it is an object of the presentinvention to provide a preceding material for pumping, which can extendthe pumping distance with the very small amount of feeding thereof.

Means to Solve the Problem

To achieve the objects mentioned above, according to Claim 1 of thepresent invention, there is a preceding material for pumping,characterized by comprising an added cellulose fiber, and having calciumcarbonate as a main component.

Moreover, according to Claim 2 of the present invention, with regard tothe preceding material for pumping as claimed in Claim 1, a part or thewhole of the calcium carbonate is calcium carbonate recovered fromsludge of ready-mixed concrete.

Moreover, according to Claim 3 of the present invention, with regard tothe preceding material for pumping as claimed in Claim 1 or Claim 2, theadded volume of cellulose nanofiber is 0.005 weight percent or more.

Moreover, according to Claim 4 of the present invention, with regard tothe preceding material for pumping as claimed in any one Claim amongClaim 1 to Claim 3, paper sludge is added to the preceding material forpumping.

Moreover, according to Claim 5 of the present invention, with regard tothe preceding material for pumping as claimed in any one Claim amongClaim 1 to Claim 4, erythorobic acid is added to the preceding materialfor pumping.

And moreover, according to Claim 6 of the present invention, with regardto the preceding material for pumping as claimed in any one Claim amongClaim 1 to Claim 5, color pigment is added to the preceding material forpumping.

Effect of the Invention

As described above, according to Claim 1 of the present invention, thereis the preceding material for pumping, characterized by comprising theadded cellulose fiber, and having calcium carbonate as the maincomponent. Therefore, a thin lubricant layer of a uniform thickness maybe formed in the inside of a piping for a long distance, whereby thepumping distance may be extended.

Moreover, according to Claim 2 of the present invention, with regard tothe preceding material for pumping as claimed in Claim 1, a part or thewhole of the calcium carbonate is calcium carbonate recovered fromsludge of ready-mixed concrete. Therefore, in addition to the aboveeffect, it is also possible to utilize the waste effectively.

Moreover, according to Claim 3 of the present invention, with regard tothe preceding material for pumping as claimed in Claim 1 or Claim 2, theadded volume of cellulose nanofiber is 0.005 weight percent or more.Therefore, the above effect may be accomplished securely.

Moreover, according to Claim 4 of the present invention, with regard tothe preceding material for pumping as claimed in any one Claim amongClaim 1 to Claim 3, paper sludge is added to the preceding material forpumping. Therefore, the separation from the pumped ready-mixed concreteis performed effectively.

Moreover, according to Claim 5 of the present invention, with regard tothe preceding material for pumping as claimed in any one Claim amongClaim 1 to Claim 4, erythorobic acid is added to the preceding materialfor pumping. Therefore, even in the unexpected case that the precedingmaterial for pumping is mixed with the ready-mixed concrete to becasted, the compressive strength of concrete, after being casted andcured, may not be deteriorated.

And moreover, according to Claim 6 of the present invention, with regardto the preceding material for pumping as claimed in any one Claim amongClaim 1 to Claim 5, color pigment is added to the preceding material forpumping. Therefore, it is possible to distinguish the preceding materialfor pumping from the ready-mixed concrete clearly, whereby the mixing ofthe preceding material for pumping with the ready-mixed concrete, may beavoided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view showing a state that ready-mixed concrete ispumped and casted by a ready-mixed concrete pumping vehicle according toan embodiment of the present invention.

FIG. 2 is a sectional view schematically showing a state of a precedingmaterial for pumping and ready-mixed concrete in a piping, according tothe embodiment of the present invention.

FIG. 3 is a systematic diagram showing a process of manufacturingcalcium carbonate recovered from sludge of ready-mixed concrete, yieldedin a ready-mixed concrete plant, according to the embodiment of thepresent invention.

FIG. 4 is a view explaining a method of dynamic friction forcecomparative test according to the embodiment of the present invention.

FIG. 5 is a graphic chart showing a result of dynamic friction forcetest of a preceding material made of mortar, according to the embodimentof the present invention.

FIG. 6 is a graphic chart showing a result of dynamic friction forcetest of the preceding material for pumping according to the embodimentof the present invention.

FIGS. 7(a) and 7(b) are views showing a method and results ofready-mixed concrete pumping distance comparative test according to theembodiment of the present invention, in which, FIG. 7 (a) is a viewshowing the ready-mixed concrete pumping distance where the precedingmaterial for pumping made of mortar was used, and FIG. 7 (b) is a viewshowing the ready-mixed concrete pumping distance where the precedingmaterial for pumping according to the embodiment of the presentinvention was used.

FIGS. 8(a) and 8(b) are views showing results of ready-mixed concretepumping distance comparative test according to the embodiment of thepresent invention, in which, FIG. 8 (a) is a view showing theready-mixed concrete pumping distance where the preceding material forpumping was used, in which cellulose nanofiber is excluded from thepreceding material for pumping according to the embodiment of thepresent invention, and FIG. 8 (b) is a view showing the ready-mixedconcrete pumping distance where the preceding material for pumpingaccording to the embodiment of the present invention was used.

MODE(S) FOR CARRYING OUT THE INVENTION

Now, an embodiment of the present invention will be explained withreference to FIG. 1 to FIG. 8. FIG. 1 is a view showing a state thatready-mixed concrete is pumped to and casted in a destined place by aready-mixed concrete pumping vehicle 1, wherein a squeeze-type pump 5and a hopper 7 are installed on a vehicle main body 3 of the ready-mixedconcrete pumping vehicle 1. Moreover, an extendible boom 9 is installedon the vehicle main body 3. The boom 9 comprises a plurality of arms 11,etc.

A piping 13 is connected to the pump 5, and the piping 13 comprises aplurality of steel pipes, of which head has a flexible synthetic rubberhose connected thereto, so as to be extended to a destined place alongthe boom 9.

For reference, depending on the type of site, the steel pipes mayfurther be extended beyond the head of the boom 9, by connectingadditional steel pipes.

Ready-mixed concrete 15 (as illustrated in FIG. 2) is fed into thehopper 7, from a ready-mixed concrete mixer vehicle (not shown). Theready-mixed concrete 15, which has been fed into the hopper 7, is pumpedby the pump 5 and the piping 13 to the destined place, at which thecasting is performed.

When pumping of the ready-mixed concrete 15, as illustrated in FIG. 15,a preceding material 21 for pumping is used. In this structure, thepreceding material 21 for pumping is poured in advance of pouring of theready-mixed concrete 15, so as to form a thin lubricant layer 23 of auniform thickness on the inner peripheral surface of the piping 13. Theready-mixed concrete 15 is pumped via the inner side of the lubricantlayer 23.

For reference, FIG. 2 is a sectional view schematically showing a stateof the preceding material 21 for pumping and the ready-mixed concrete 15in a piping 13.

The preceding material 21 for pumping includes cellulose nanofiber addedthereto, and in the embodiment of the present invention, calciumcarbonate (CaCO₃) is used as a main raw material, to which cellulosenanofiber is added, and furthermore, paper sludge, erythorobic acid(C₆H₈O₆), and/or fluorescent pigment as an example of color pigment, isalso added. This structure will be explained in details hereinafter.

First, with regard to calcium carbonate, this is composed of porouscalcium carbonate, hydrotalcite-containing porous calcium carbonate,and/or sedimentary calcium carbonate.

The porous calcium carbonate has been prepared, for example, bytreatment of ready-mixed concrete sludge yielded in a ready-mixedconcrete plant, with the particle size adjustment and the ingredientadjustment. The particle of the porous calcium carbonate has alubrication effect (bearing effect) because of its round corners, andhas an excellent water absorbing performance because of its porousstructure, whereby contributing to the good fluidity of the precedingmaterial 21 for pumping, in itself.

For reference, the ready-mixed concrete sludge means residue aftercollection of aggregate out of, for example, sludge water yielded fromcleaning of ready-mixed concrete mixer vehicle or cleaning of agitatortruck, or out of returned concrete or residual concrete.

The hydrotalcite-containing porous calcium carbonate has also beenprepared, for example, by treatment of the ready-mixed concrete sludgeyielded in the ready-mixed concrete plant, with the particle sizeadjustment and the ingredient adjustment, and is fine powder having ahigh fineness, composed solely of hydrotalcite and calcite. Thehydrotalcite-containing porous calcium carbonate has the same effect asthat of clay material, and takes on a role of viscosity adjustment aswell as contributes to suppression of material separation, with regardto the preceding material 21 for pumping according to the presentembodiment.

The hydrotalcite is a compound expressed as the general formula[M²⁺._(1-x)M3³⁺._(x)(OH)₂][A^(n−)._(x/n).mH₂O]. M²⁺ is to express ametal ion of bivalence, M3³⁺ is to express a metal ion of trivalence,and A^(n−)._(x/n) is to express an interlamellar anion, respectively.Moreover, x is in the range of 0<x<1, n is the valence of A, and m is inthe range of 0≤m≤1.

The porous calcium carbonate and the hydrotalcite-containing porouscalcium carbonate are produced, for example, by “Collection Method andApparatus of Usable Particulate from Waste” as disclosed in the OfficialGazette of Japanese Patent No. 4501098. FIG. 3 is a systematic diagramshowing structural outlines of a collecting apparatus of Japanese PatentNo. 4501098. First, muddy waste 31, which has been yielded in aready-mixed concrete plant, is introduced in a deposit device 33, so asto deposit ready-mixed concrete sludge. Next, the deposited ready-mixedconcrete sludge is taken out, and is introduced in a dewatering device35, so as to perform the dewatering process until reaching the watercontent of 60% or less. Next, the dewatered sludge is taken out, and isdried (by natural drying or machine drying) until reaching the watercontent of 25% or less, and next, is introduced in a grinder 37, so asto be ground until reaching the particle size of 30 mm or less.

Next, the dried and ground sludge is fed into a cyclone classifier 41 bydried sludge feeding device 39, so as to be finely ground until reachingthe particle size of 250 μm or the specific surface area of 4000 cm²/gor finer (by Blaine air permeability measurement). Furthermore, theobtained finely ground particle is caught by a catching device 43. Thecatching device 43 is provided with two-staged bag filters 45, 47, inwhich, the first bag filter 45 catches the porous calcium carbonate, andthe second bag filter 47 catches the hydrotalcite-containing porouscalcium carbonate. These porous calcium carbonate and thehydrotalcite-containing porous calcium carbonate are dropped and caughtonto a belt conveyor 49.

The sedimentary calcium carbonate is a synthetic calcium carbonate, andis fine powder calcium carbonate having a uniform particle shape bychemical treatment. Because of the uniform particle shape of thesedimentary calcium carbonate, when the preceding material 21 forpumping forms the lubricant layer 23, the surface of the lubricant layer23 becomes uniform and smooth.

The cellulose nanofiber is fiber made of cellulose, and is a material ofwhich fiber width has been refined to a nano-order level, that is a fewhundredth or less of 1 μm, and in general, can be obtained from wood inabundance. The cellulose nanofiber has the characteristics oflight-weight, strong, ultrafine fiber, large specific surface area,small dimensional change due to heat, excellent gas barrier property,exhibiting specific viscosity in the water, and environment-friendly.

The cellulose nanofiber spreads in a matrix state in the precedingmaterial 21 for pumping, and consequently, the sedimentation of fineparticle, of which specific weight is larger than the water, isprevented, and in addition, a thixotropic property (a property in which,the viscosity of fluid becomes smaller upon application of a specificpressure thereto, and after passing of a specific time, the viscosityreturns to the original state) is imparted to the preceding material 21for pumping. Accordingly, it is possible to prevent the precedingmaterial 21 for pumping from being aggregated in the piping 13, andfurthermore, because of having the fluidity upon application of forcethereto, it is possible to adapt to the change of delivery velocity.Moreover, if solidified cement paste, etc., is remaining in the piping13 due to insufficient cleaning, there is a risk of clogging of thepiping, because the large volume of water content in the precedingmaterial 21 for pumping will be taken out to the solidified cementpaste. However, in the case of the preceding material 21 for pumpingaccording to the present embodiment, with the addition of the cellulosenanofiber, there is no risk of excessive sticking, etc., to the innerperipheral surface of the piping 13, of the preceding material 21 forpumping, and it is possible to prevent the clogging of the piping.

The paper sludge as described above is, in particular, micro-sizedcellulose fiber derived from paper sludge, and contributes, with regardto the preceding material 21 for pumping, to the material separationfrom the ready-mixed concrete 15.

The erythorobic acid as described above has the effect that, even wherethe preceding material 21 is mixed with the ready-mixed concrete, thedeterioration of compressive strength of the ready-mixed concrete may beprevented.

The fluorescent pigment as described above is, in particular, a colorpigment, and for example, a color pigment made by DayGlo Color Corp.,USA. With the addition of such an organic fluorescent pigment to thepreceding material 21 for pumping, it is possible to clearly distinguishthe preceding material 21 for pumping, from the ready-mixed concrete 15.

With regard to the volume of each component of the preceding material 21for pumping, according to an example 1 of the embodiment of the presentinvention, the porous calcium carbonate derived from the ready-mixedconcrete sludge is 20 kg, the fine powder of the hydrotalcite-containingporous calcium carbonate derived from the ready-mixed concrete sludge is2 kg, the sedimentary calcium carbonate is 12 kg, the paper sludge is 5kg, the water is 25 liter, the cellulose nanofiber is 100 g, theerythorobic acid is 15 g, and the fluorescent pigment is 90 g. Theabove-described 100 g of cellulose nanofiber is composed of 5 g ofcellulose nanofiber and 95 g of water. Therefore, as shown in theformula (1), in the case of the example 1, approximately 0.008 weightpercent of the cellulose nanofiber is added thereto:

5 g/64.205 kg≈0.00008  (1)

The preferable additional volume of the cellulose nanofiber is 0.005weight percent or more.

In the case of the example 1, as the cellulose nanofiber, “BiNFi-s”(registered trademark) biomass nanofiber, made by Sugino MachineLimited, Japan, is used. This biomass nanofiber has been produced fromcellulose, chitin, chitosan and carboxymethyl-cellulose (CMC) byultrahigh pressure water-jet technology treatment. The cellulosenanofiber used in the example 1 is ultrafine fiber produced fromcellulose by ultrahigh pressure water-jet technology treatment, of whichdiameter is 20 nm, and of which length is a few μm.

The function of the present embodiment will be explained on the basis ofthe above structure.

With reference to FIG. 1, first, the preceding material 21 for pumpingaccording to the embodiment is filled in an outlet of the hopper 7, andsubsequently the ready-mixed concrete 15 is fed thereto. They are pumpedto a destined place by the pump 5 and the piping 13.

For reference, where the pump 5 is not the squeeze type, but is thepiston type, then, the preceding material 21 for pumping is filled inthe inside of the piping of the pump 5 on the discharging side.

In the inside of the piping 13, it is assumed that the situation asillustrated in FIG. 2 is occurring. First, the preceding material 21 forpumping exists at the head of the inner space of the piping 13, and thethin lubricant layer 23 of a uniform thickness has been formed on theinner peripheral surface of the piping 13.

Meanwhile, with regard to the ready-mixed concrete 15, which is to bepumped subsequently to the preceding material 21 for pumping, the coarseaggregate, etc., having the large cubic volume and density, gathers tothe center portion (shown by reference numeral 15 a in FIG. 2), and thesand gathers to the outer periphery thereof (shown by reference numeral15 b in FIG. 2), and the cement gathers to the still outer peripherythereof (shown by reference numeral 15 c in FIG. 2), and the watergathers to the still outer periphery thereof (shown by reference numeral15 d in FIG. 2). Moreover, the preceding material 21 for pumpingintrudes into the top end portion of the ready-mixed concrete 15. Inthis state, the ready-mixed concrete 15 is pumped smoothly along theinner periphery of the lubricant layer 23 of the preceding material 21for pumping.

It should be noted that FIG. 2 is the view merely showing the stateschematically and in the actual cases, it is assumed that the boundariesof these layers are intricating with each other.

After pumping through the piping 13, the ready-mixed concrete 15 iscasted from the head of the piping 13, into e.g. a mold frame (notshown). At that time, first, the preceding material 21 for pumping,which has been pumped in advance, is disposed. Since the precedingmaterial 21 for pumping has been colored by the organic fluorescentpigment, it is possible to confirm by visual recognition of the color offluid discharged from the head of the piping 13. Then, after confirmingthat the preceding material 21 for pumping has been disposed completely,the ready-mixed concrete 15, pumped thereafter, is casted in the moldframe.

The state in the inside of the piping 13 will be explained more indetails.

Since the preceding material 21 for pumping, to which the cellulosenanofiber has been added, has a specific thixotropic property, it isassumed that the following phenomenon is occurring among the precedingmaterial 21 for pumping, the ready-mixed concrete 15 and the piping 13:that is, the relative velocity between the outermost periphery of thepreceding material 21 for pumping and the inner peripheral surface ofthe piping 13 is large, and causing the large shearing force. Therefore,the outermost peripheral area of the preceding material 21 for pumpingexhibits the excellent fluidity and moistens the inner surface of thepiping 13, which serves as the lubricant layer 23. On the other hand,the relative velocity in the inside of the preceding material 21 forpumping decreases gradually from the outermost periphery toward the axiscenter, and the preceding material 21 for pumping proceeds in a state ofgel-mass like solid bar. Strictly speaking, since the volume of thepreceding material 21 for pumping is reduced in the course of moisteningof the inner peripheral surface of the piping 13, with the furtherproceeding in the piping 13, the top end portion of the precedingmaterial 21 for pumping goes forward in a shape that the solid bar iscut slantingly namely in a state that the contact line thereof with theinner peripheral surface of the piping 13 draws a parabola.

Meanwhile, the ready-mixed concrete 15 proceeds, in a state that the topend portion thereof pushes the rear end of the preceding material 21 forpumping, and the outermost periphery of the ready-mixed concrete 15 doesnot become in contact with the inner peripheral surface of the piping13, but goes forward, in a state of being in contact with the lubricantlayer 23 formed by the preceding material 21 for pumping. Therefore, thewater content of the ready-mixed concrete 15 will not be taken out tothe inner peripheral surface of the piping 13. Consequently at the topend of the ready-mixed concrete 15, the advanced proceeding of thecoarse aggregate is suppressed. Even in the case of advanced proceedingof the coarse aggregate, since the coarse aggregate intrudes into thesolid-bar state of the preceding material 21 for pumping, theready-mixed concrete 15 will not become in contact with the innerperipheral surface of the piping 13, and instead, the preceding material21 for pumping is pressed against the inner peripheral surface of thepiping 13, whereby the forming of the lubricant layer 23 is enhanced.Consequently the pumping distance is extended.

With regard to the series of functions as described above, in the insideof the piping 13, the dynamic friction force of the preceding material21 for pumping keeps a constant level, for example as compared with thatof mortar, and therefore, the ready-mixed concrete 15 is pumpedsmoothly.

At the time of such a pumping, the paper sludge serves as a cushion.

Moreover, since the cellulose nanofiber imparts the thixotropic propertyto the preceding material 21 for pumping, the fluidity in a static stateis suppressed, and consequently for example, in the case of pumping inthe downstream gradient, it is possible to prevent the advancedproceeding of the preceding material 21 for pumping.

Furthermore, with the cellulose nanofiber, it is possible to maintainthe dispersibility of fine particle in the preceding material 21 forpumping.

Next, since various tests were performed for the purpose of confirmingof the performance of the preceding material 21 for pumping according tothe present embodiment, the results of these tests will be explained.First, a comparative test of dynamic friction force was performed,between a preceding material for pumping made of mortar, serving as acomparative example, and the preceding material 21 for pumping accordingto the example 1 of the present embodiment.

First, the test method will be explained with reference to FIG. 4. Aresin plate 31, of which thickness is 0.255 mm, was placed, and thepaste of the mortar-made preceding material for pumping, serving as thecomparative example, was coated on the resin plate 31, in the coatingthickness of 0.230 mm. Thereafter, a sliding piece 35 was placed on sucha coating film 33, and a load cell 37 was connected to the sliding piece35 via a string body 36. Thus, the sliding piece 35 was slid, via theload cell 37 and the string body 36, in a direction as shown by an arrowa of FIG. 4, and the dynamic friction force at that time was measured bythe load cell 37. The test velocity was 100 mm/min, and the load rangewas 2.5 N.

The same test was also performed by coating the preceding material 21for pumping according to the example 1.

The results are shown in FIG. 5 and FIG. 6. In FIG. 5, the horizontalaxis shows the distance (mm) and the longitudinal axis shows the dynamicfriction force (N), and the variation of dynamic friction force is shownwith regard to the mortar-made preceding material for pumping, servingas the comparative example. In FIG. 6, the horizontal axis shows thedistance (mm) and the longitudinal axis shows the dynamic friction force(N), and the variation of dynamic friction force is shown with regard tothe preceding material 21 for pumping, according to the example 1. As isclear from FIG. 5 and FIG. 6, the dynamic friction force of thepreceding material 21 for pumping, according to the example 1, issmaller than the dynamic friction force of the comparative example madeof mortar.

Moreover, with regard to the mortar-made preceding material for pumping,serving as the comparative example, the waveform is waving largely, andon the other hand, with regard to the preceding material 21 for pumping,according to the example 1, the waveform is stable. Therefore, in thecase of the preceding material 21 for pumping, according to the example1, as compared with the mortar-made preceding material for pumping,serving as the comparative example, it is possible to maintain theconstant dynamic friction force.

With the synergetic effect of these functions, the ready-mixed concrete15 may be pumped smoothly for the long distance.

Next, a comparative test of pumping distance of ready-mixed concrete,will be explained with reference to FIGS. 7(a) and 7(b). As illustratedin FIGS. 7(a) and 7(b), two ready-mixed concrete pumping vehicles 1, 1were provided, and the pipings 13, 13 were connected thereto,respectively for the length of approximately 100 m. Thereafter, withregard to one ready-mixed concrete pumping vehicle 1, the mortar-madepreceding material for pumping, serving as the comparative example, andthe ready-mixed concrete, were pumped subsequently. Similarly withregard to the other ready-mixed concrete pumping vehicle 1, thepreceding material 21 for pumping, according to the example 1 of thepresent embodiment, and the ready-mixed concrete, were pumpedsubsequently. The volume of the preceding material for pumping as thecomparative example, and the volume of the preceding material forpumping according to the example 1, were both 18 liter.

With regard to the piping 13, in particular, thirty-one steel pipes,each of which inner diameter was 107 mm and the length was 3 m, wereconnected to each other, and a flexible synthetic rubber hose, of whichlength was 7 m, was connected thereto.

Moreover, the pumping velocity was 10 m³/h.

As a result, when the mortar-made preceding material for pumping,serving as the comparative example, was used, the clogging occurredaround the point of 48 m. On the other hand, when the preceding material21 for pumping, according to the example 1, was used, the pumping couldbe performed for the whole length of approximately 100 m. It is assumedthat, this is because of the effective forming of the lubricant layer 23on the inner peripheral surface of the piping 13, in the case of usingof the preceding material 21 for pumping, according to the example 1.

For reference, the inner peripheral area of the piping 13 used for thetest, was approximately 34.243 m², and it is assumed that the precedingmaterial 21, of which volume was 18 liter, formed the lubricant layer 23by spreading uniformly.

Next, a comparative test of pumping distance, depending on whether thecellulose nanofiber is provided or not, will be explained with referenceto FIGS. 8(a) and 8(b). First, two types, namely a cellulose nanofiberadditive type, and a cellulose nanofiber non-additive type, wereprepared. The additive type was the preceding material 21 for pumpingaccording to the example 1 of the present embodiment, and thenon-additive type was the preceding material 21 for pumping according tothe example 1, from which the cellulose nanofiber had been excluded.

Moreover, the ready-mixed concrete pumping vehicles 1, 1 were provided.Each of the ready-mixed concrete pumping vehicles 1, 1 is a piston-typevehicle, of which boom length was 30 m, and had been cleaned by aircleaning only.

The reason for using of the piping 13, which had been cleaned by aircleaning only, will be explained as follows. There are two types ofcleaning, namely the cleaning by using the water, and the cleaning byusing the air. If the cleaning by using the water is selected, thecleanness in the inside of the piping 13 will be improved. However,there may be a situation that, because of difficulty in using the largevolume of cleaning water, etc., the cleaning was settled by air cleaningonly. In the case of air cleaning, there may be the case that thesolidified cement paste, etc., is remaining in the piping. Accordingly,in order to confirm that a desired pumping performance can be obtainedin such a poor condition, in the present comparative test of pumpingdistance, the piping 13, which had been cleaned by air cleaning only wasused purposely.

With regard to one ready-mixed concrete pumping vehicle 1, the cellulosenanofiber non-additive type of preceding material for pumping, and theready-mixed concrete 15, were pumped subsequently. Similarly with regardto the other ready-mixed concrete pumping vehicle 1, the precedingmaterial for pumping according to the example 1, and the ready-mixedconcrete 15, were pumped subsequently.

As a result, when the cellulose nanofiber non-additive type of precedingmaterial for pumping was used, the clogging occurred at the intermediatepoint (around the point of 15 m). On the other hand, when the precedingmaterial 21 for pumping, according to the example 1, was used, thedelivery could be performed without clogging.

The present embodiment has the following effects.

First, with the addition of the cellulose nanofiber to the precedingmaterial 21 for pumping, even in the case that the inner surface of thepiping 13 is somewhat rough because of the solidified cement paste,etc., remaining in the piping 13, the thin lubricant layer 23 of auniform thickness may be formed in the inside of the piping 13, wherebythe pumping distance of the ready-mixed concrete 15 may be extended.

In particular, in the case of the present embodiment, since thecellulose nanofiber is added for 0.008 weight percent or more, the aboveeffect may be obtained securely.

Moreover, since the paper sludge is added to the preceding material 21for pumping, it is possible to effectively separate the precedingmaterial 21 for pumping, from the ready-mixed concrete 15 to be pumped.

Moreover, since the erythorobic acid is added to the preceding material21 for pumping, even in the unexpected case that the preceding material21 for pumping is mixed with the ready-mixed concrete 15 to be casted,the compressive strength of concrete, after being casted and cured, maynot be deteriorated.

Moreover, since the calcium carbonate recovered from the sludge iscontained in the calcium carbonate, it is possible to utilize theconcrete sludge effectively.

Moreover, since the porous calcium carbonate in the calcium carbonaterecovered from the sludge has the round corners, it is possible toobtain the bearing effect, and because of its porous structure, theexcellent water absorbing performance may be exhibited, wherebycontributing to the good fluidity of the preceding material 21 forpumping, in itself.

Moreover, the hydrotalcite-containing porous calcium carbonate,contained in the calcium carbonate recovered from the sludge, has theexcellent powder fineness, and contains the hydrotalcite. Thesecharacteristics contribute to the viscosity adjustment of the precedingmaterial 21 for pumping, and also contributes to the suppression ofmaterial separation.

Moreover, the sedimentary calcium carbonate contained in the calciumcarbonate contributes to the forming of the uniform and smooth surfaceof the lubricant layer 23.

And moreover, since the organic fluorescent pigment is added, it ispossible to clearly distinguish the preceding material 21 for pumping,from the ready-mixed concrete 15. Accordingly it is possible to preventthe preceding material 21 for pumping, from being mixed with theready-mixed concrete 15 to be casted.

The present invention is not limited to the embodiment as describedabove.

First, in the embodiment as described above, with regard to the volumeof each component comprising the preceding material for pumping, anexample is shown as the example 1. However, the present invention is notlimited to such an example, and it is needless to say that the addedvolume of the cellulose nanofiber is not limited to such an example,either. Moreover, with regard to the manufacturing method thereof, otherthan the aqueous counter collision method of “BiNFi-s” (registeredtrademark), various types of cellulose nanofiber may be used, which hasbeen manufactured by physical treatment such as the grinding method orthe ball milling method, or by chemical treatment such as the catalyticoxidation method with regard to TEMPO (2, 2, 6, 6-tetramethylpiperidine1-oxyl).

Moreover, in the embodiment as described above, a part of the calciumcarbonate is the calcium carbonate recovered from the sludge. However,the present invention is not limited to such an example, and it is alsopossible to use the calcium carbonate recovered from the sludge, as thewhole component. It is needless to say that there may be a structure inwhich the calcium carbonate recovered from the sludge is not used atall.

Moreover, in the embodiment as described above, the calcium carbonaterecovered from the sludge is obtained by treatment of the muddy waste inthe ready-mixed concrete plant. However, the present invention is notlimited to such an example, and it is also possible to use any othertype of muddy waste.

Moreover, in the embodiment as described above, the explanation was madewith regard to the pumping of the ready-mixed concrete as an example.However, the present invention is not limited to such an example, and itis also possible to adopt the present invention to the pumping of othertypes of paste-state fluid, mixed with mass objects and having a risk ofclogging, for example, the pumping of the mass of coal and fine powderof coal dispersing in the water.

INDUSTRIAL APPLICABILITY

The present invention relates to the preceding material for pumping,which is used during pumping and casting of the ready-mixed concrete byusing, for example, the ready-mixed concrete pumping vehicle. Moreparticularly, the present invention relates to the preceding materialfor pumping, in which the pumping distance can be extended by usingcellulose nanofiber. The present invention is suitable, for example, forcasting of the ready-mixed concrete at various construction sites.

EXPLANATION OF REFERENCE NUMERALS AND SIGNS

-   -   1 Ready-mixed Concrete Pumping Vehicle    -   3 Vehicle Main Body    -   5 Pump    -   7 Hopper    -   9 Boom    -   11 Arm    -   13 Piping    -   15 Ready-mixed Concrete    -   21 Preceding Material    -   23 Lubricant Layer

1. A preceding material for pumping, characterized by comprising anadded cellulose fiber, and having calcium carbonate as a main component.2. The preceding material for pumping as claimed in claim 1, wherein, apart or the whole of the calcium carbonate is calcium carbonaterecovered from sludge of ready-mixed concrete.
 3. The preceding materialfor pumping as claimed in claim 1, wherein, the added volume ofcellulose nanofiber is 0.005 weight percent or more.
 4. The precedingmaterial for pumping as claimed in claim 1, wherein, paper sludge isadded to the preceding material for pumping.
 5. The preceding materialfor pumping as claimed in claim 1, wherein, erythorobic acid is added tothe preceding material for pumping.
 6. The preceding material forpumping as claimed in claim 1, wherein, color pigment is added to thepreceding material for pumping.